1. Field of the Invention
This invention relates to a multiple rotational position sensor. More particularly, it relates to a novel improvement therein which consists in that a casing having a stator is rotationally interlocked with a rotor shaft of a casing having a stator for sensing the absolute value of the many number of rotations of the rotor shaft.
2. Prior Art
While a variety of rotational position sensors of the above type, such as resolver or synchro is employed, the construction of a resolver produced by the present Applicant is shown herein in FIG. 1, as typical of these sensors.
Referring to FIG. 1, the numeral 1 denotes a generally tubular casing, and a rotor shaft 4 is carried for rotation by a pair of bearings 2 and 3 provided on either ends of the casing 1.
On the rotor shaft 4, a rotor 5 for a rotary transformer having a rotor winding 5a for a rotational transformer and a rotor 6 for a resolver having a rotor winding 6a for a resolver are mounted with a predetermined spacing in-between as set by a spacer 7.
On the inner wall 1a of the casing 1 in register with the rotor 5 for the rotary transformer, there is provided a stator 8 having a stator winding 8a for the rotary transformer, with the stator winding 8a for the rotary transformer being inductively coupled with the stator winding 8a for the rotational transformer.
On the inner wall 1a of the casing 1, in register with the rotor 6 for the resolver, there is provided a stator 9 having a stator winding 9a for the resolver. The stator 8 for the rotational transformer and the stator 9 for the resolver are maintained at a predetermined distance from each other by a spacer 10. The rotor 6 for the resolver and the stator 9 for the resolver make up a resolver section 11.
The above described resolver operates in the following manner.
When an exciting signal is supplied from the stator winding 8a of the rotational transformer, this exciting signal is supplied from the rotor winding 5a for the rotational transformer to the rotor winding 6a for the resolver for exciting the rotor winding 6a for the resolver.
When the rotor shaft 4 is revolved as it is coupled to a rotational member of a machine tool, not shown, there is obtained a rotational angle signal proportionate to the rotational angle of this rotor shaft 4.
The above described resolver of the prior art suffers from the following disadvantages. That is, when the state of rotation over a plural number of times of revolutions of a rotor shaft is to be detected, the resolver need be connected by way of a speed reducing unit to a separate resolver with resulting increase in the overall size of the system and manufacture costs so that the recent demand for reduced size and costs cannot be met.